It's a little delivery robot, with a GPS locator so you can get your stuff delivered anywhere, anytime.

Then she saw it too. A bouncing machine. Something very much like a camouflage-painted kangaroo.

It was crossing the hills with vast, unerring, twenty-meter leaps. A squat metal sphere, painted in ragged patches of dun and olive drab. It had a single thick, pistoning, metal leg.

The bounding robot whipped that single metal leg around with dreadful unerring precision, like some nightmare one-legged pirate. It whacked its complex metal foot against the earth like a hustler's cue whacking a pooi ball, and it bounded off instantly, hard. The thing spent most of its time airborne, a splotchy cannonball spinning on its axis and kicking like a flea against the Texan earth. It was doing a good eighty klicks an hour. As it got closer she saw that its underside was studded with grilled sensors.

It gave a final leap and, God help her, a deft little somersault, and it landed on the earth with a brief hiss of sucked-up impact. Instantly, a skinny little gunmetal tripod flicked Out from beneath it, like a triple set of hinged switchblades.

And there it sat, instantly gone as quiet as a coffee table, not ten meters away from them.

"All right," she said. "What is that thing?"

"It's a dope mule. From my friends in Matamoros."

"Oh, Jesus."

"Look," he said, "relax. It's just a cheaper street version of Charlie, your car! Charlie's a smuggler's vehicle, and this is a smuggler's vehicle. It's just that instead of having two hundred smart spokes and driver's seats and roll bars like that big kick-ass car does, it's only got one spoke. One spoke, and a gyroscope inside, and a global positioning system." He shrugged. "And some mega chip inside so it never runs into anything and no cop ever sees it."

"Oh," she groaned. "Yeah, this is great, Alex."

"It'll carry, I dunno, maybe forty kilos merchandise. No big deal. Dope people have hundreds of these things now. They don't cost much to make, so it's like a toy for 'em.

"Why didn't you tell me about this?"

"Are you kidding? Since when do I ask your permission to do anything?" He walked up to the mule.

"Tamperproof! Put in the wrong password, and the sucker explodes on the spot and destroys all the evidence! And what's more-if you're not, like, their friend? Or they're tired of dealing with you? Then sometimes they just booby-trap it, and blow you away the second you touch the keypad."

He laughed. "Don't look so glum. That's all just legend, really. Doper brag talk. The dope vaqueros hardly ever blow anyone up. You and me both know the border doesn't mean anything anymore. There are no more borders. Just free and open markets!" He chuckled merrily. "They can send me whatever the hell they want. Dope, explosives, frozen human hearts, who cares? They're just another delivery service."

Alex punched a long string of numbers, with exaggerated care, into a telephone keypad welded into the top of the mule. The robot mulled the matter over, then hissed open on a stainless-steel hinge, showing a big rubber 0-ring around its midsection.